In a previous recipe, we discussed M:N trunk routing, and we said that associating multiple gateways with a single Mediation Server adds resiliency and flexibility. In this recipe, we will see how to obtain three different results: load balancing, failover, and least cost routing.
Note
There are some limitations and compatibility requirements while implementing the solutions explained in this recipe. We can find a short explanation about them in the TechNet post M:N trunk in Lync Server 2013 at http://technet.microsoft.com/en-us/library/gg398971.aspx.
In the following recipe, we will add some gateways to our scenario and we will assume that they are already configured. The international.wonderland.lab gateway is the least costly gateway for international calls from UK to France. To enable failover routing, we will add another gateway failover.wonderland.lab.